MOVING PREISACH MODEL ANALYSIS OF NANOCRYSTALLINE SMFECO

Nanocrystalline SmFeCo, prepared by mechanically alloying the elementa ry powders and subsequent annealing (600 degrees C/15 min), showed rem anence enhancement (eta=I-r/I-s=0.67) and H-c= 18.6 kOe. Starting from the ac-demagnetized state, minor hysteresis loops were determined for magnetic fields up to 70 kOe for numerical calculation of the Preisac h function p(h(c),h(u)), where h(c) and h(u) are the elementary loop c oercive field and interaction field. The numerically determined irreve rsible part of p(h(c),h(u)) had a form indicating that it could be fac tored: p(irr)(h(c),h(u))=f(h(c))g(h(u)), where f(h(c)) and g(h(u)) are log-normal and Gaussian distributions. An analytic expression for p(h (c),h(u))=f(h(c))g(h(u)) + P-rev was fitted to experimental hysteresis curves. The analytic expression for p(h(c),h(u)) was used with the mo ving Preisach model to calculate minor loops and Henkel plots. Agreeme nt between theory and experiment was very good. (C) 1997 American Inst itute of Physics.